A.N.T. Farm to Torchwood

The Hashimoto soda brand is featured on both shows along with the companies founder Mr. Hashimoto

Mr. Moseby from The Suite Life was on Jessie

Jessie and Austin & Ally crossed over

Austin and Ally appear on an episode of Girl Meets World. Bringing the Disney Channel Live Action Universe into the Westphall Universe

Continuation of Boy Meets Wolrd

Sabrina the Teenage Witch also crossed over with Boy Meets World on several other occasions.

Sabrina from Sabrina the Teenage Witch visited Cher from Clueless in the episode "Mr. Wright."

Hakeem and Niecy from Moesha went to the prom with Cher and Sean from Clueless.

The Parkers was a spinoff of Moesha

The Hughleys crossed over with The Parkers.

The Drew Carey Show's Mimi appeared in an episode of The Hughleys

The Drew Carey Show did a cross over with Coach.

Newhart's Larry, Darryl and Darryl squatted in Coach's Hayden and Christine's home

The Bob Newhart Show's Bob Hartley woke up after dreaming the entire series Newhart during Newhart's finale.

The Bob Newhart Show's Elliot Carlin visited the psych ward at St Elsewhere's St Eligius Hospital.

St Elsewhere's Dr Turner was investigated for murder by Homicide's Pembleton and Bayliss.

Homicide's John Munch questioned The X-Files' The Lone Gunmen.

The X-Files? Cigarette Smoking Man and Buffy the Vampire Slayer's Spike both smoked Morley cigarettes.

Angel was a spin-off of Buffy the Vampire Slayer

In the Red Dwarf episode "Psirens", the crew of the Red Dwarf come across a space ship graveyard which includes a Weyland-Utani ship, connecting it with Angel.

The TARDIS from Doctor Who appears in the hangar bay of the Red Dwarf - it can be seen during the launch of Starbug in the episode "Thanks for the Memory"

Torchwood is a spin-off focusing on the covert Torchwood Institute and the crossover character Captain Jack Harkness